Walls, ceilings, floors, partitions, bathtub surround and the like are commonly constructed from multiple pieces of board (sometimes referred to as “panels”). The board may be composed of any of a variety of materials, including but not limited to, cementitious materials such as, for example, cement or gypsum. Typically, when two pieces of board abut each other in use, a gap or seam referred to as a joint is defined between boards. It is well known to fill and coat the joints with a specially prepared adhesive called “joint compound.” Two types of joint compound are known in the art: a setting type and drying type, which is available in a ready-mix form. This process is also used to make repairs of defects, such as uneven surfaces, holes, depressions, gaps, dents, and other imperfections including those around electrical boxes, piping and duct work, as well as corners created by the intersection of drywall boards.
It is well known in the art that finishing a joint between boards using a joint tape typically involves three steps. First a thin layer of joint compound is applied to the boards over the joint, and the tape is embedded into it. This step is commonly referred to as the embedding step. Next, a second coat of joint compound is applied over the embedded joint tape. This step is commonly referred to as the fill step. The second coat of joint compound typically extends approximately two inches beyond the edges of the joint tape. Finally a third coat of joint compound is applied over the first two coats, where the third coat typically extends even further out from the edges of the joint tape. This is commonly referred to as the finish step. Because paper joint tape will swell in the presence of the moisture from the joint compound, the second and third coats of joint compound cannot be applied until the previous coat of joint compound and the joint tape are fully dry, which often takes as much as 24 hours. This means that as many as three days are required to finish a board joint. Where the tape is a self-adhesive tape, only steps (ii) and (iii) are required, and therefore up to two full days are needed to finish a joint.
Joint tape adds strength and crack resistance as well as smooth concealment at flat joints and inside corners. Conventionally, three types of joint tape have been employed: a simple kraft paper strip; a woven glass fiber tape; and a non-woven glass fiber tape. Kraft paper strips and non-woven glass fiber tape are adhered to the surfaces of board such as drywall by a bedding coat of joint compound or they are self-adhered. Woven glass fiber tape is typically of the self adhesive type, but can also be fixed to the wall with staples. Once a paper joint tape has been applied, one must wait as much as a day for the joint compound and tape to be fully dry before the next coat of joint compound can be applied.
Glass fiber tape is nonswellable and resists stretching and wrinkles. However nonwoven glass fiber tapes suffer from low tensile strength and are prone to cracking when used with conventional joint compounds. Woven glass fiber tapes have sufficient tensile strength, but the board joints produced with drying-type joint compound are prone to cracking, and thus woven glass fiber tapes are only recommended for use with setting type compounds.
Accordingly, there remains a need in the art for an improved joint tape that has high strength and reduced expansion due to moisture. In addition, there remains a need for an improved method of finishing joints between pieces of board that reduces or eliminates the need to wait until the joint compound has dried. The invention provides such a joint tape and method. These and other advantages of the invention as well as additional inventive features will be apparent from the description of the invention provided herein.